Throughout an average football game, the officials of the game must resort to sideline markers to establish whether the offense has advanced the ball by the required distance. Generally, a pair of poles connected by a 30 foot long chain is employed so that a first of these poles is located on the sidelines at the approximate location of the initial line of scrimmage and the second pole is moved as far forward as possible to indicate the 10 yard first down distance. Each time this measurement is made, the game must be delayed and the yard markers must be carried from the sidelines to the place on the field where the official has “spotted” the ball.
In the game of American football, progress made by the offensive team is measured by what is referred to as the “chain system.” The chain system includes three main components which will be referred to as the rear rod, the forward rod, and the box. The rear rod marks the beginning of the current set of downs. The box is a pole with an indicator of the current down, and is placed at the position of the ball before each play. The forward rod marks a distance ten yards from the rear rod, in a direction towards the defense's goal-line. The forward rod and rear rod (always referred to as “sticks”) are connected to one another by a chain which is exactly 10 yards in length when taut. The chain system requires 3 employees, often referred to as the “chain gang” or “chain crew,” to operate. Each of the 3 employees is responsible for one of the rear rod, forward rod, and box. While the system only requires 3 employees, it is often the case that additional employees are present.
The chain system has a number of drawbacks. For example, there must be a trained chain gang, which requires costs associated with the training as well as for managing the game. Further, when attempting to determine if a player has gained a first down in a close-call situation, the chain gang is required to run out to the spot of the ball. This allows for the possibility of human error being injected into the measuring process if the chain gang does not run exactly perpendicular from where they were standing on the sideline. Moreover, there is an injury risk for both the chain gang and the players. If a player runs out of bounds near where the chain gang is positioned, he could collide with either one of the members of the chain gang or their equipment, potentially injuring the player or the chain gang. Further, if the chain gang is hit and lose their placement, it may be difficult or impossible to return to the correct placement on the field. This adds additional uncertainty into the game. Additionally, once a first down is achieved and the ball is placed on the field by the official, the placement of the rear rod is determined visually by the member of the chain gang holding the rear rod. This introduces further uncertainty and potential human error in the proper placement of the football.
While attempts at improving the chain system have been made, none have been adopted and none entirely replace the need for the chain gang entirely. For example, U.S. Pat. No. 6,751,880 entitled “System and Method for Operating Groups of Lasers to Project a Visible Line Demarcation within Discrete Regions of an Athletic Field,” U.S. Pat. No. 6,796,041 entitled “System for Operating One or More Lasers to Project a Visible Line onto a Grass-Covered Surface,” U.S. Pat. No. 7,219,438 entitled “System for Operating One or More Suspended Laser Projectors to Project a Temporary Visible Image onto a Surface,” and U.S. Pat. No. 8,713,808 entitled “System and Method for Projecting a Visible Line on an Athletic Field Surface” are all directed to using laser projection systems to supplant the chain gang.
However, these systems have various drawbacks. For example, some of these systems require hanging bulky and potentially dangerous systems above the playing field. In the event these systems were to accidently fall, they could seriously injure a player. Further, this system is expensive. It would require the installation of support structures and wires to support the lasers. Additionally, the space above the field is already crowded, as various lines and cameras, such as the Skycam, are already present above the field. It would require substantial effort to coordinate the hanging laser systems with the already present camera systems without causing interference of either the laser system or camera system. Additionally, these systems do not alleviate the need for the chain gang. Rather, the above discussed systems merely add a new component, a laser first down marker, to the chain gang system. Moreover, none of these systems have been adopted by professional sports teams.
Still other prior art systems have been described but have never been adopted, largely for practical reasons as their implementation and function are suspect. For example, fifty years ago, U.S. Pat. No. 3,752,588 to Chapman involves the use of projectors that are located at the sidelines and several feet above the field level. The lasers are mounted for oscillation in a vertical plane and the projected, low intensity beam developed by each must strike the field at points of reference lying on an imaginary line of demarcation defined by the intersection of the vertical plane with the field surface. Accordingly, it is necessary for the operator to manually position the projector for each reference point established.
Other laser systems have been described in U.S. Pat. No. 3,741,62 to Pioch entitled “Visible Line Marker” (hereinafter “Pioch”) and U.S. Pat. No. 4,090,708 to McPeak entitled “Apparatus for Marking Football Fields” (hereinafter “McPeak”), each of which are herein incorporated by reference in their entirety. The system described in Pioch requires the use of elevated rails, which increases the chances of injury to a player on the sideline. Moreover, the system described in Pioch still requires a crew of some kind to continuously move each of the laser housings on the track to the desired location. Similarly, the system described in McPeak, rather than replacing the sticks currently utilized, are merely an upgraded version of the sticks. For example, while the system does project a demarcation line for convenience, it does not improve game measurements and is not automated. Accordingly, it still requires a chain gang to operate the system on the sidelines.
Another drawback associated with the aforementioned systems is that the low-intensity output of these lasers is far too low to be visible by the players, let alone by an audience in, for example, a stadium setting. Indeed, the aforementioned systems are intended for use only in making a first down measurement determination after each close play. As it turns out, players intent on getting the ball past the first yard line—and focused on the sideline markers long enough to be “blindsided” by the defense—have suffered very serious neck and back injuries.
Television networks have recently implemented an image pre-processing system which allows viewers of televised football games to see a so-called “virtual” first down line that digitally projects, in real time, a visible line onto video frames recorded by the television camera, the line being displayed on a viewer's television set so that it appears to extend between the first down sideline markers. Unfortunately, neither the players, game officials, nor the fans attending such games can actually see this virtual line. It is thus reasonable to conclude that given the rapid and widespread adoption of a virtual visible line marking system—whose enjoyment is strictly limited to television viewers, it has heretofore been deemed impossible or impracticable to project a real, visible line onto the grassy surfaces which characterize most athletic fields.
A continuing need therefore exists for a visible line or image marking system that is simple to operate, accurate enough to allow its use by officials at sporting events, and of sufficient intensity to be viewed by players, large audiences, and television viewers alike.
A need also exists for a system capable of projecting, onto surfaces that are characterized by uniform and/or non-uniform topological features, a line which can be seen from different perspectives and from considerable distances—even in daylight conditions.
A need also exists for a system that is capable of projecting a line which, though intense enough to be seen from a wide range of viewing angles, conforms to all applicable eye-safety regulations such as those promulgated by the FDA's Center for Diagnostic and Radiological Health (CDRH).
A need also exists for a system that is flexible enough so that it can be used to project images comprising one or more linear or curvilinear line segments, with the images being either monochromatic or multicolored, as desired.
Accordingly, there exists a need for a laser system which can feasibly replace the chain system which is simpler, cheaper, and safer than the current state of the art.